JP2001234144A - Adhesive for carpentry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-viscosity adhesive for carpentry which is excellent in water resistance and low-temperature stability. SOLUTION: This adhesive comprises an aqueous emulsion which contains, as the disperse phase, a polymer having vinyl ester monomer units, and is prepared by using, as the dispersant, a vinyl alcohol polymer having at least 1.7 mol% 1,2-glycol bonds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a woodworking adhesive having a high viscosity, excellent water resistance, and excellent low-temperature storage stability.

[0002]

2. Description of the Related Art Conventionally, polyvinyl alcohol (hereinafter referred to as P
VA) is widely used as a protective colloid for emulsion polymerization of ethylenically unsaturated monomers, particularly vinyl ester monomers represented by vinyl acetate, and is used as a protective colloid. Vinyl ester aqueous emulsion obtained by emulsion polymerization is used for various adhesives for paper, woodworking and plastics, various binders for impregnated paper and non-woven products, admixtures, jointing materials, paints, paper processing And widely used in fields such as fiber processing. Such an aqueous emulsion generally has a low viscosity by adjusting the degree of saponification of the PVA-based polymer, has a viscosity close to a Newtonian flow, and has a relatively good water resistance. Since it has a high viscosity and relatively low temperature dependence of emulsion viscosity, it has been awarded for various uses. However, some of the aqueous emulsions lack fluidity (high-speed coating properties), have poor water resistance, have a large temperature dependence of emulsion viscosity, and have a marked increase in emulsion viscosity at low temperatures. It is known that it has drawbacks and that these properties largely depend on the PVA-based polymer used in the emulsion polymerization.

That is, PV as a dispersant for emulsion polymerization
The A-based polymers generally include so-called "fully saponified PVA" having a saponification degree of about 98 mol% and "partially saponified PVA" having a saponification degree of about 88 mol%. Although the fluidity (high-speed coating property) is good, there is a disadvantage that the viscosity of the emulsion at the time of leaving at low temperature is remarkably increased and gelation is easily caused. On the other hand, when the latter PVA-based polymer is used, the emulsion has an improved viscosity at low temperatures and a tendency to gel at low temperatures, but has a disadvantage of poor water resistance. In order to improve such disadvantages, both PVA-based polymers are used in combination, and PVA-based polymers having an intermediate saponification degree between the two are used. Sex was not satisfied at the same time. In addition, emulsions used for woodworking include:
A vinyl acetate emulsion using partially saponified PVA as a protective colloid is generally used. At present, there is a problem that the adhesiveness to the material is insufficient.

[0004]

SUMMARY OF THE INVENTION The present invention provides a high-viscosity emulsion under such circumstances,
It is an object of the present invention to provide a woodworking adhesive having excellent low-temperature storage stability.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop an adhesive for woodworking having the above-mentioned preferable properties. As a result, a polymer or vinyl ester comprising a vinyl ester monomer unit has been obtained. An adhesive using an aqueous emulsion containing a polymer having a monomer unit and an ethylene unit as a dispersoid and a vinyl alcohol polymer having 1.7 mol% or more of 1,2-glycol bonds as a dispersant is described above. The inventors have found that the object is satisfied, and have completed the present invention.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A vinyl alcohol polymer having 1.7 mol% or more of 1,2-glycol bonds used as a dispersant for an aqueous emulsion used in the present invention is:
When polymerizing the vinyl ester-based monomer, a vapor of the vinyl ester-based monomer or solvent or a non-condensable gas is introduced from the outside and pressurized in the polymerization machine, and a temperature higher than the boiling point of the reaction solution, for example, 75 to It is obtained by saponifying a vinyl ester polymer polymerized at a temperature of 200 ° C. by a conventional method. The content of 1,2-glycol bonds is 1.7 mol%
It is necessary to be at least 1.8 mol%, more preferably at least 1.9 mol%.
When the content of the 1,2-glycol bond is less than 1.7 mol%, there is a concern that the storage stability at low temperatures is lowered. Further, the content of the 1,2-glycol bond is preferably 4 mol% or less, more preferably 3.5 mol% or less, and most preferably 3.2 mol% or less. Where 1,2-
The content of the glycol bond is determined from the analysis of the NMR spectrum.

Here, examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and the like. In general, vinyl acetate is preferably used.

The dispersant may be a copolymer of an ethylenically unsaturated monomer copolymerizable within a range not to impair the effects of the present invention. Such ethylenically unsaturated monomers include, for example, acrylic acid, methacrylic acid, fumaric acid, (anhydride) maleic acid, (anhydride) itaconic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl- ( 3-acrylamide-
3-dimethylpropyl) -ammonium chloride, acrylamide-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, N-vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride , Tetrafluoroethylene, sodium vinyl sulfonate, sodium allyl sulfonate and the like.
Further, in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid, a vinyl ester-based monomer such as vinyl acetate is copolymerized with ethylene, and a terminal-modified product obtained by saponifying the copolymer may also be used. it can.

The degree of saponification of a vinyl alcohol polymer having 1,2-glycol bonds of 1.7 mol% or more used as a dispersant for an aqueous emulsion used in the woodworking adhesive of the present invention is not particularly limited, but is usually 80. It is used in an amount of at least 90 mol%, more preferably at least 90 mol%, even more preferably at least 95 mol%. Saponification degree 80
When the amount is less than mol%, there is a concern that the water solubility, which is an intrinsic property of the vinyl alcohol-based polymer, is reduced. The degree of polymerization of the vinyl alcohol-based polymer is also not particularly limited, but is usually in the range of 100 to 8000,
3000 is more preferably used. When the degree of polymerization is less than 100, the characteristics as a PVA protective colloid are not exhibited, and when it exceeds 8,000, there is a problem in industrial production of the vinyl alcohol polymer.

The vinyl ester monomer constituting the dispersoid in the aqueous emulsion used in the present invention includes vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and the like. preferable.

In a preferred embodiment, the dispersoid in the aqueous emulsion used in the present invention is a polymer comprising a vinyl ester monomer unit or a polymer comprising a vinyl ester monomer unit and an ethylene unit. Further, within a range not to impair the object of the present invention, ethylenically unsaturated monomers,
A monomer such as a diene monomer may be copolymerized. These monomers include olefins such as propylene and isobutylene, halogenated olefins such as vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride; vinyls such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate. ester,
Acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 2-hydroxyethyl acrylate, etc., methyl methacrylate, ethyl methacrylate, methacrylic acid Butyl, 2-ethylhexyl methacrylate, dodecyl methacrylate,
Methacrylic esters such as 2-hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and quaternaries thereof, furthermore, acrylamide, methacrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, Acrylamide monomers such as acrylamide-2-methylpropanesulfonic acid and its sodium salt,
Examples include styrene-based monomers such as styrene, α-methylstyrene, p-styrenesulfonic acid, and sodium and potassium salts, N-vinylpyrrolidone, and diene-based monomers such as butadiene, isoprene, and chloroprene. Further, divinylbenzene, tetraallyloxyethane, N, N'-methylenebis-acrylamide, 2,
2'-bis (4-acryloxypolyethoxyphenyl) propane, 1,3-butylene glycol diacrylate,
1,5-pentanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate,
Triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, allyl methacrylate, 1,4
-Butanediol diacrylate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol dimethacrylate,
1,6-hexanediol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, 2,2 -Bis (4-methacryloxypolyethoxyphenyl) propane, aluminum methacrylate, zinc methacrylate, calcium methacrylate, magnesium methacrylate, N, N'-m-phenylenebismaleimide, diallyl phthalate, triallyl cyanurate, triallyl Isocyanurate, triallyl trimellitate, diallyl chlorendate, ethylene glycol diglycidylate Polyfunctional monomers such as Le acrylate.

The aqueous emulsion used in the present invention is, for example, an aqueous solution of a vinyl alcohol polymer having 1.7 mol% or more of 1,2-glycol bonds as a dispersant, and an ethylenically unsaturated monomer and a diene At least one monomer selected from monomers is added temporarily or continuously, and polymerization of an azo-based polymerization initiator, hydrogen peroxide, peroxide-based polymerization initiator such as ammonium persulfate and potassium persulfate is initiated. It is obtained by adding an agent and performing emulsion polymerization.

The amount of the PVA-based polymer used is not particularly limited, but 100% by weight of a polymer containing at least one monomer unit selected from the above-mentioned ethylenically unsaturated monomers and diene-based monomers. Preferably 3 to 2 parts
0 parts by weight, more preferably 5 to 15 parts by weight. If the amount is less than 3 parts by weight, the polymerization stability may decrease. If the amount exceeds 20 parts by weight, the storage stability of the obtained emulsion may decrease.

The aqueous emulsion obtained by the above method can be used as it is for the adhesive of the present invention.
If necessary, conventionally known various emulsions can be added and used as long as the effects of the present invention are not impaired. In addition, as a dispersant in the aqueous emulsion used in the present invention, the aforementioned 1,2-glycol bond is 1.7.
Although a PVA-based polymer having at least mol% is used, a conventionally known anionic, nonionic or cationic surfactant, a PVA-based polymer, hydroxyethylcellulose, or the like can be used in combination, if necessary.

The woodworking adhesive of the present invention is excellent in adhesiveness to wood materials because of its high viscosity, and excellent in water resistance and low-temperature storage stability. It is widely used for bonding wood materials such as wood board adhesives, woodworking adhesives for secondary processing (kneading), woodworking such as general woodworking, and adhesives for producing laminates such as plywood.

[0016]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following Examples and Comparative Examples, “parts” and “%” mean on a weight basis unless otherwise specified. In addition, the water resistance and storage stability of the obtained emulsion were evaluated in the following manner.

(Evaluation of Woodworking Adhesive) (1) Water Resistance of Film The obtained aqueous emulsion was subjected to P
It was cast on ET and dried for 7 days to obtain a dry film of 500 μm. This film was punched out to a diameter of 2.5 cm, and the sample was immersed in water at 20 ° C. for 24 hours to determine the water absorption and elution rate of the film. Elution rate (%) = {1- (absolute dry weight of film after immersion) / (absolute dry weight of film before immersion)} × 100 Water absorption rate (%) = {(water absorption weight of film after immersion) / (before immersion) Of the film before immersion; weight of the film before immersion (water content)-
皮膜 Coating weight (water content) before immersion × Coating water content (%) / 10
0｝ Film moisture content: The film (a sample different from the sample immersed in water at 20 ° C.) is completely dried at 105 ° C., and the moisture content of the film is determined in advance. -Absolute dry weight of the film after immersion: The weight of the film after immersion absolutely dried at 105 ° C.・ Water absorption weight of film after immersion: After immersing the film after immersion, the water on the film was wiped off with gauze and weighed. (2) Normal adhesive strength (birch wood) The obtained woodworking adhesive was applied to birch wood (straight grain) at 150 g / m2.
2 were applied, bonded together, and pressed under a load of 7 kg / m 2 for 16 hours, then released, and cured at 20 ° C. and 65% RH for 5 days. The normal adhesion strength of this test piece was 20 ° C., 65
Measured under% RH. (3) Hot water adhesive strength (birch wood) The obtained woodworking adhesive was applied to birch wood (straight grain) at 150 g / m.
2 were applied, bonded together, and pressed under a load of 7 kg / m 2 for 16 hours, then released, and cured at 20 ° C. and 65% RH for 5 days. After curing, it was immersed in warm water at 60 ° C. for 3 hours, and the compressive shear strength was measured in a wet state. Immersion peeling of plywood adhesion test (secondary processing of plywood) The obtained woodworking adhesive was applied to Rawan plywood (class 1 plywood, five-ply laminate) at 2000 g / m2 and bonded together for 7 kg.
/ M2 for 3 hours, then release
Cured at 65 ° C. and 65% RH for 5 days. After curing, it was immersed in warm water of 60 ° C. for 3 hours, and the immersion peeling test was performed in a wet state. ○ No peeling, Δ Partial peeling, × Complete peeling (5) Leaving stability test The viscosity change after 90 days when the woodworking adhesive was left at 5 ° C. was observed.

Production Example 1 2940 g of vinyl acetate, 60 g of methanol and 0.088 g of tartaric acid were charged into a 5 L pressurized reaction vessel equipped with a stirrer, a nitrogen inlet, and an initiator inlet, and reacted while bubbling with nitrogen gas at room temperature. The operation of increasing the tank pressure to 2.0 MPa, leaving the mixture to stand for 10 minutes, and then releasing the pressure was repeated three times to replace the system with nitrogen. 2,2′-azobis (cyclohexane-1-carbonitrile) (V-
40) was dissolved in methanol to prepare a solution having a concentration of 0.2 g / L, and nitrogen was replaced by bubbling with nitrogen gas. Next, the temperature in the polymerization tank was raised to 120 ° C. The reaction tank pressure at this time was 0.5 MPa. Then
The polymerization was started by injecting 2.5 ml of the above initiator solution.
During the polymerization, the polymerization temperature was maintained at 120 ° C., and V-40 was continuously added at 10.0 ml / hr using the above initiator solution to carry out the polymerization. The reactor pressure during polymerization is 0.5MPa
Met. After 3 hours, the mixture was cooled to stop the polymerization. At this time, the solid content concentration was 24%. Next, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution of polyvinyl acetate (concentration: 33%). Methanol was added to the obtained polyvinyl acetate solution, and 400 g of a methanol solution of polyvinyl acetate (100 g of polyvinyl acetate in the solution) adjusted to have a concentration of 25% was added at 40 ° C. with 11.6 g (polyacetic acid). The molar ratio (M
R) 0.025) alkaline solution (NaOH 10% methanol solution) was added for saponification. In about 2 minutes after the addition of the alkali, the gelled system was crushed with a crusher,
After letting the saponification proceed for 1 hour, methyl acetate 10
The remaining alkali was neutralized by adding 00 g. After confirming the completion of the neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid PVA obtained by filtration.
Was added and washed at room temperature for 3 hours. 3
After repetition of the number of times, the PVA obtained by centrifugal drainage is left in a dryer at 70 ° C. for 2 days to dry PVA (PVA-1).
I got The degree of saponification of the obtained PVA (PVA-1) (D
H) was 98 mol%. Further, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer after polymerization is saponified at an alkali molar ratio of 0.5, and the pulverized one is left at 60 ° C. for 5 hours to advance saponification. After that, Soxhlet washing with methanol was performed for 3 days, followed by drying under reduced pressure at 80 ° C. for 3 days to purify purified PVA.
I got The average degree of polymerization (DP) of the PVA is determined by a conventional JIS.
It was 1700 when measured according to K6726.
The amount of 1,2-glycol bound to the purified PVA was 500 MH
It was 2.2 mol% as determined by measurement with a z proton NMR (JEOL GX-500) apparatus.

Production Example 2 2940 g of vinyl acetate, 60 g of methanol and 0.088 g of tartaric acid were charged into a 5 L pressurized reaction tank equipped with a stirrer, a nitrogen inlet, and an initiator inlet, and reacted while bubbling with nitrogen gas at room temperature. The operation of increasing the tank pressure to 2.0 MPa, leaving the mixture to stand for 10 minutes, and then releasing the pressure was repeated three times to replace the system with nitrogen. 2,2′-azobis (cyclohexane-1-carbonitrile) (V-
40) was dissolved in methanol to prepare a solution having a concentration of 0.2 g / L, and nitrogen was replaced by bubbling with nitrogen gas. Next, the temperature in the polymerization tank was raised to 120 ° C. The reaction tank pressure at this time was 0.5 MPa. Then
The polymerization was started by injecting 2.5 ml of the above initiator solution.
During the polymerization, the polymerization temperature was maintained at 120 ° C., and V-40 was continuously added at 10.0 ml / hr using the above initiator solution to carry out the polymerization. The reactor pressure during polymerization is 0.5MPa
Met. After 3 hours, the mixture was cooled to stop the polymerization. At this time, the solid content concentration was 24%. Next, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution of polyvinyl acetate (concentration: 33%). To 400 g of a methanol solution of polyvinyl acetate (100 g of polyvinyl acetate in the solution) adjusted to a concentration of 25% by adding methanol to the obtained polyvinyl acetate solution, 2.3 g (polyacetic acid) at 40 ° C. Molar ratio (MR) to vinyl acetate unit in vinyl
(0.005) of an alkali solution (a 10% methanol solution of NaOH) and 1.4 g of water were added for saponification. About 20 minutes after the addition of the alkali, the gelled system was pulverized by a pulverizer and left for 1 hour to progress the saponification. Then, 1000 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of the neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid PVA obtained by filtration and washed at room temperature for 3 hours. After the above washing operation was repeated three times, P
VA is left in a dryer at 70 ° C. for 2 days to dry PVA (
PVA-2) was obtained. The degree of saponification of the obtained PVA (PVA-2) was 88 mol%. Further, saponification of a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer after polymerization at an alkali molar ratio of 0.5,
After the pulverized product was left at 60 ° C. for 5 hours to progress saponification, Soxhlet washing with methanol was carried out for 3 days, followed by drying at 80 ° C. for 3 days under reduced pressure to purify the purified PV.
A was obtained. The average degree of polymerization of the PVA was determined according to the standard method of JIS K6.
It was 1700 when measured according to 726. The 1,2-glycol bond amount of the purified PVA was 2.2 mol% as determined by measurement with a 500 MHz proton NMR (JEOL GX-500) apparatus.

Production Example 3 2850 g of vinyl acetate, 150 g of methanol and 0.086 g of tartaric acid were charged into a 5 L pressurized reaction tank equipped with a stirrer, nitrogen inlet and initiator inlet, and reacted at room temperature while bubbling with nitrogen gas. The operation of increasing the tank pressure to 2.0 MPa, allowing the tank to stand for 10 minutes, and then releasing the pressure is performed in 3 steps.
The system was repeatedly replaced with nitrogen. 2,2 'as initiator
A solution of -azobis (N-butyl-2-methylpropionamide) in methanol was prepared at a concentration of 0.1 g / L, and nitrogen was replaced by bubbling with nitrogen gas. Next, the temperature inside the polymerization tank was raised to 145 ° C. At this time, the reaction tank pressure was 1.0 MPa. Then
The polymerization was started by injecting 15.0 ml of the above initiator solution. During the polymerization, the polymerization temperature was maintained at 145 ° C., and 2,2′-azobis (N-butyl-2-methylpropionamide) was continuously added at 15.8 ml / hr using the above initiator solution to carry out the polymerization. Carried out. The reactor pressure during polymerization is 1.0M
Pa. After 4 hours, the mixture was cooled to stop the polymerization. At this time, the solid content concentration was 35%. Then 30 ° C
Unreacted vinyl acetate monomer was removed while occasionally adding methanol under reduced pressure to obtain a methanol solution of polyvinyl acetate (concentration: 33%). Methanol was added to the obtained polyvinyl acetate solution, and 400 g of a methanol solution of polyvinyl acetate (100 g of polyvinyl acetate in the solution) adjusted to a concentration of 25% was added with 11.6 g at 40 ° C.
An alkaline solution (10% NaOH) in a molar ratio (MR) of 0.025 with respect to vinyl acetate units in polyvinyl acetate.
% Methanol solution) for saponification. What was gelled in about 3 minutes after the alkali addition was pulverized with a pulverizer,
After letting the saponification proceed for 1 hour, methyl acetate 10
The remaining alkali was neutralized by adding 00 g. After confirming the completion of the neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid PVA obtained by filtration.
Was added and washed at room temperature for 3 hours. 3
After repeating this process twice, the PVA obtained by centrifugal drainage was left in a dryer at 70 ° C. for 2 days to obtain dry PVA (PVA-3). The degree of saponification of the obtained PVA (PVA-3) is 9
8 mol%. Further, after polymerization, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer was saponified at an alkali molar ratio of 0.5, and the pulverized one was left at 60 ° C. for 5 hours to progress saponification. After that, Soxhlet washing with methanol was performed for 3 days, followed by drying under reduced pressure at 80 ° C. for 3 days to obtain purified PVA.
When the average degree of polymerization of the PVA was measured according to a conventional method JIS K6726, it was 1000. The purified PVA 1
500 MHz proton NMR for 2-glycol bond
(JEOL GX-500) It was 2.5 mol% as determined from measurement with an apparatus.

Production Example 4 2400 g of vinyl acetate, 600 g of methanol and 49.3 g of vinylene carbonate were charged into a 5 L pressurized reaction tank equipped with a stirrer, a nitrogen inlet, and an initiator inlet, while bubbling with nitrogen gas at room temperature. The reaction tank pressure was 2.
The operation of increasing the pressure to 0 MPa, leaving the mixture to stand for 10 minutes, and then releasing the pressure was repeated three times to replace the system with nitrogen. A 1.0 g / L solution of α, α′-azobisisobutyronitrile dissolved in methanol as an initiator was prepared, and nitrogen was replaced by bubbling with nitrogen gas. Next, the temperature inside the polymerization tank was raised to 90 ° C. At this time, the pressure in the reaction tank was set at 0.1.
It was 4 MPa. After adjusting the internal temperature of the polymerization tank to 90 ° C., 3.0 ml of the initiator solution was injected to start polymerization. During the polymerization, the polymerization temperature was maintained at 90 ° C., and α, α′-azobisisobutyronitrile was continuously added at 4.9 ml / hr using the above-mentioned initiator solution to carry out the polymerization. The reactor pressure during the polymerization was 0.4 MPa. After 4 hours, the mixture was cooled to stop the polymerization. The solid concentration at this time is 38%
Met. Then, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution of polyvinyl acetate (concentration: 33%). 400 g of a methanol solution of polyvinyl acetate (100 g of polyvinyl acetate in the solution) adjusted to a concentration of 25% by adding methanol to the obtained polyvinyl acetate solution.
Then, at 40 ° C., 46.4 g (molar ratio (MR) of 0.10 with respect to the vinyl acetate unit in polyvinyl acetate) of an alkali solution (10% methanol solution of NaOH) was added to perform saponification. The gel that was gelled in about 1 minute after the addition of the alkali was pulverized with a pulverizer and left for 1 hour to progress the saponification. Then, 1000 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, a white solid PVA obtained by filtration was obtained.
Was added and methanol was added and washed at room temperature for 3 hours. After repeating the above washing operation three times, the PVA obtained by centrifugal dewatering was left in a dryer at 70 ° C. for 2 days to obtain dry PVA (PVA-4). The obtained PVA (PVA
-4) was 99.5 mol%. Further, after polymerization, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer was saponified at an alkali molar ratio of 0.5, and the pulverized one was left at 60 ° C. for 5 hours to progress saponification. After that, Soxhlet washing with methanol was performed for 3 days, followed by drying under reduced pressure at 80 ° C. for 3 days to obtain purified PVA. The degree of polymerization of the PVA is determined by the conventional method J
It was 1200 when measured according to IS K6726. The amount of 1,2-glycol bound to the purified PVA was 50
It was 2.5 mol% as determined by measurement with a 0 MHz proton NMR (JEOL GX-500) apparatus.

Production Example 5 Vinyl acetate 20 was placed in a 5 L four-neck separable flask equipped with a stirrer, a nitrogen inlet, an initiator inlet, and a reflux condenser.
00 g, methanol 400 g, vinylene carbonate 7
8.8 g was charged, and the system was replaced with nitrogen while bubbling nitrogen at room temperature for 30 minutes. The internal temperature of the above polymerization tank is 60 ° C.
Then, 0.9 g of α, α'-azobisisobutyronitrile was added as an initiator to initiate polymerization. During the polymerization, the polymerization temperature was maintained at 60 ° C., and after 4 hours, the polymerization was stopped by cooling. At this time, the solid content concentration was 55%. Then, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution of polyvinyl acetate (concentration: 33%). Methanol was added to the obtained polyvinyl acetate solution to adjust the concentration to 25% by adding methanol.
0 g (100 g of polyvinyl acetate in the solution) and 46.4 g (molar ratio (MR) to vinyl acetate unit in polyvinyl acetate unit: 0.10) of alkali solution (Na) at 40 ° C.
(10% methanol solution of OH) was added for saponification. The gel that was gelled in about 1 minute after the addition of the alkali was pulverized with a pulverizer and left for 1 hour to progress the saponification. Then, 1000 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of the neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid PVA obtained by filtration, and the mixture was allowed to wash at room temperature for 3 hours. After repeating the above washing operation three times, the PV obtained by centrifugal drainage was obtained.
A in a dryer at 70 ° C. for 2 days to dry PVA (PV
A-5) was obtained. The degree of saponification of the obtained PVA (PVA-5) was 99.5 mol%. Further, after polymerization, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer was saponified at an alkali molar ratio of 0.5, and the pulverized one was left at 60 ° C. for 5 hours to progress saponification. After that, Soxhlet washing with methanol was performed for 3 days, followed by drying under reduced pressure at 80 ° C. for 3 days to obtain purified PVA. The degree of polymerization of the PVA is determined by a standard method of JIS K6.
It was 1200 when measured according to 726. The 1,2-glycol bond amount of the purified PVA was 3.0 mol% as determined by measurement with a 500 MHz proton NMR (JEOL GX-500) apparatus.

Example 1 300 ml of ion-exchanged water was placed in a 1-liter glass polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet.
PVA-1 obtained in Production Example 1 (degree of polymerization 1700,
26 g of a saponification degree of 98.0 mol% and a 1,2-glycol content of 2.2 mol%) were charged and completely dissolved at 95 ° C. Next, the PVA aqueous solution was cooled and replaced with nitrogen.
After the temperature was raised to 60 ° C. while stirring at 0 rpm, 4.4 g of a 10% aqueous solution of tartaric acid and 3 g of a 5% aqueous hydrogen peroxide solution were used.
After adding a shot (at a molar ratio of 0.015 to vinyl acetate), 26 g of vinyl acetate was charged to initiate polymerization. 30 minutes after the start of the polymerization, completion of the initial polymerization was confirmed. Tartaric acid 1
After adding 0.9 g of a 0% aqueous solution and 3 g of a 5% aqueous hydrogen peroxide solution in a shot, 234 g of vinyl acetate was continuously added over 2 hours to complete the polymerization. After cooling, the solution was filtered using a 60-mesh stainless steel wire mesh. As a result, a polyvinyl acetate emulsion having a solid content of 47.3% was obtained. 5 parts of dibutyl phthalate was added to and mixed with 100 parts by weight of this emulsion (Em-
1). This emulsion was evaluated by the method described above. Table 1 shows the results.

Comparative Example 1 Instead of using PVA-1 used in Example 1, PVA-6 produced by a conventional method (PVA-117 manufactured by Kuraray Co., Ltd .;
(Em-2) having a solids concentration of 47.1% was obtained in the same manner as in Example 1 except that the polymerization degree was 1700, the saponification degree was 98.0%, and the 1,2-glycol content was 1.6 mol%. Obtained. This emulsion was evaluated by the method described above. The results are shown in Table 1.

Example 2 A 1-liter glass polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer and a nitrogen inlet was charged with 300 ion-exchanged water.
PVA-2 obtained by Production Example 2 (degree of polymerization 1700,
13 g of a saponification degree of 88.0 mol% and a 1,2-glycol content of 2.2 mol%) were charged and completely dissolved at 95 ° C. Next, the PVA aqueous solution was cooled and replaced with nitrogen.
After the temperature was raised to 60 ° C. while stirring at 0 rpm, 18 g of a 10% aqueous solution of tartaric acid and 26 g of vinyl acetate were charged, and 85 g of 1% aqueous hydrogen peroxide was continuously added over 2.5 hours to initiate polymerization. . After 30 minutes from the start of the polymerization, completion of the initial polymerization was confirmed, and 234 g of vinyl acetate was continuously added over 2 hours. After the completion of the addition of vinyl acetate, 4.8 g of a 1% aqueous hydrogen peroxide solution was added by a shot to complete the polymerization. After cooling, the solution was filtered using a 60-mesh stainless steel wire mesh. The polymerization stability was evaluated in the same manner as in Example 1 based on the residual amount of filtration after filtration. As a result, a polyvinyl acetate emulsion having a solid content of 47.6% was obtained. Further, 5 parts of dibutyl phthalate was added to and mixed with 100 parts by weight of the obtained emulsion (Em-3). This emulsion was evaluated by the method described above. The results are shown in Table 1.

Comparative Example 2 Instead of using PVA-3 used in Example 2, PVA-7 produced by a conventional method (manufactured by Kuraray Co., Ltd.)
PVA-217; degree of polymerization 1700, degree of saponification 88.0 mol%,
Except that 1,2-glycol content (1.6 mol%) was used, (Em-
4) was obtained. This emulsion was evaluated by the method described above. The results are shown in Table 1.

Example 3 Instead of using PVA-1 used in Example 1, PVA-3 obtained by Production Example 3 (polymerization degree: 1000, saponification degree: 98.0 mol%, 1,2-glycol content: 2 .
(Em-5) having a solid concentration of 47.7% was obtained in the same manner as in Example 1 except that 5 mol%) was used. This emulsion was evaluated by the method described above. The results are shown in Table 1.

Comparative Example 3 PVA-8 (produced by Kuraray Co., Ltd.) produced by a conventional method instead of using PVA-1 used in Example 1
PVA-110; degree of polymerization 1000, degree of saponification 98.5 mol%,
Except that 1,2-glycol content (1.6 mol%) was used, the solid content of 47.6% (Em-
6) was obtained. This emulsion was evaluated by the method described above. The results are shown in Table 1.

Example 4 Instead of using PVA-1 used in Example 1, PVA-4 obtained in Production Example 4 (degree of polymerization 1200, degree of saponification 99.5 mol%, content of 1,2-glycol 2 .
(Em-7) having a solid content concentration of 47.8% was obtained in the same manner as in Example 1 except that 5 mol%) was used. This emulsion was evaluated by the method described above. The results are shown in Table 1.

Example 5 Instead of using PVA-1 used in Example 1, PVA-5 obtained in Production Example 6 (degree of polymerization 1200, degree of saponification 99.5 mol%, 1,2-glycol content 3 .
(Em-8) having a solid content concentration of 47.8% was obtained in the same manner as in Example 1 except that 0 mol%) was used. This emulsion was evaluated by the method described above. The results are shown in Table 1.

Example 6 A pressure-resistant autoclave equipped with a nitrogen inlet, a thermometer, and a stirrer was charged with 100 parts of a 7.5% aqueous solution of PVA-1, heated to 60 ° C., and replaced with nitrogen. After charging 80 parts of vinyl acetate, ethylene was pressurized to 45 kg / cm ² and 2 g of a 0.5% aqueous hydrogen peroxide solution and 0.3 g of a 2% Rongalite aqueous solution were injected to initiate polymerization. When the residual vinyl acetate concentration became 10%, ethylene was released, the ethylene pressure was set to 20 kg / cm ^2, and 0.3 g of a 3% aqueous hydrogen peroxide solution was injected to complete the polymerization. No aggregation during polymerization, excellent polymerization stability, solid concentration 4
An ethylene-vinyl acetate copolymer emulsion (Em-9) having 9.5% and an ethylene content of 10% by weight was obtained. Evaluation was performed by the method described above. Table 1 shows the results.

Comparative Example 4 Instead of using PVA-1 used in Example 6, P
An ethylene-vinyl acetate copolymer emulsion (Em-10) having a solid content of 49.4% and an ethylene content of 10% by weight was obtained in the same manner as in Example 4 except that VA-6 was used. Evaluation was performed by the method described above. Table 1 shows the results.

[0033]

[Table 1]

[0034]

The woodworking adhesive of the present invention has a high viscosity and is therefore excellent in adhesiveness to wood materials, and also has excellent water resistance and low-temperature storage stability. It is widely and suitably used for bonding wood materials such as glue, wood board, plywood for secondary processing (kneading), woodworking adhesives such as general woodworking, and adhesives for producing laminates such as plywood.

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Claims (2)

[Claims] 1. A woodwork comprising an aqueous emulsion containing a polymer having vinyl ester monomer units as a dispersoid and a vinyl alcohol polymer having 1,2-glycol bonds of 1.7 mol% or more as a dispersant. Adhesive. 2. The woodworking adhesive according to claim 1, wherein the dispersoid is a polymer having a vinyl ester monomer unit and an ethylene unit.